What a difference a sign makes. The sign on the left is increasingly common at junctions in the Netherlands. It indicates that cyclists will get their own green phase at the lights and that when the light is green they can travel in any direction across the junction, including diagonally.
What's more, cyclists usually get two green phases per complete sequence of the lights, meaning that they wait for less time behind a red light. This leads to cyclists getting past the lights quicker than drivers. It works very well indeed.
A couple of days ago I made a video of riding across such a junction when I visited Groningen. Also there is a video of the same junction made by the fietsberaad, the Dutch panel of experts in cycling, which demonstrates the same junction from different angles.
Please also read other later / better blog posts about simultaneous green traffic lights. Also see many other examples on this blog of infrastructure which makes cyclists' journeys faster.
Car-Sick Glasgow | Documenting the atrocious conditions for cyclists and pedestrians in Scotland's largest city